This invention relates to a tie for forming into a loop around cables and other objects.
Ties for forming into loops around cables etc. are well known. One such tie comprises an elongate strap extending from an apertured head. In use, the tie can be formed into a loop by passing the free end of the strap through the apertured head. A flexible pawl inside the head engages serrations on the strap and prevents the strap from loosening.
An advantage of such ties is that they can conveniently be formed as a one piece plastics moulding. However, a disadvantage of plastics ties is that they break relatively easily under load, particularly once the plastic has become brittle. Another disadvantage of plastics ties is that they are unsuitable for use in some environments, say where extremes of temperature exist.
Ties formed from metal are also well-known. Such ties are generally stronger and are more suitable for use in some environments. A disadvantage of metal ties is that they cannot be formed as a one-piece moulding.
WO82/02035 and U.S. Pat. No. 5,291,637 each disclose a tie comprising an apertured head and an elongate flexible strap attached at a first end thereof to the head, and a locking member in the form of a ball mounted in a cavity inside the head and arranged to engage the strap, when the second end of the strap is passed through the head aperture. The elongate flexible strap is attached to the head by folding the first end thereof through substantially 180° to form a U-shaped portion, which engages over a bottom wall of the head. A barb on the distal end of the U-shaped portion of the strap engages a location in the bottom wall of the head.
The ball is inserted into the head cavity through an open end wall of the head during assembly of the tie. A tab on the head is then folded over to close the open end wall and captively retain the ball inside the head cavity: This assembly operation is difficult and time consuming.
An alternative version of a tie using a locking member in the form of a ball is disclosed in EP0758616 which is less difficult and time consuming to assemble than the type disclosed in WO82/02035 and which is characterised in that an opening is formed in the head, through which the locking member ball is inserted during assembly of the tie, the first end of the strap extending over the opening in the head and captively mounting the locking member in the head cavity. The tie is assembled by inserting the locking member through the opening in the head prior to attaching the strap to the head.
In use ties of this type operate by means of the tie being formed into a loop around the cables or other objects to be tied and the free end of the strap inserted through the head aperture. The locking member (typically a ball, as described) engages the strap as it is pulled through the head aperture in the tightening direction. The strap is released, once it has been sufficiently tightened, thereby causing it to withdraw slightly from the head. This withdrawal movement causes the locking member ball to move to a locking position in which it becomes wedged between a wall of the head and the strap, so as to securely lock the latter to the head.
Occasionally, when inserting the free end of the strap into the aperture in the head, the leading edge can impinge against the ball at a level too high towards the equator of the ball causing the strap to buckle at its free end and snag on feeding into the head. This can prevent the tie from being used adequately. This problem can occur particularly where the free end of the strap has been damaged (kinked or buckled) prior to use.
An improved arrangement has now been devised that addresses these, and other problems.